Traumatic injury can lead to a variety of pathological manifestations at sites removed from the direct injury. During the initial period of this research project, we have developed a rat model for traumatic injury and using in vitro methods have shown that there is substantial decrease in hepatic drug metabolizing enzymes post-trauma. This research endeavor and our substantial progress in developing spin trapping techniques for the detection of biologically generated free radicals puts us in a very favorable position to continue these studies. In light of this discussion, the specific aims of this proposal are: 1) to further refine the present trauma model (infrarenal aorta ligation) by utilizing inbred rats. 2) to determine the functional significance of the observed diminished levels of in vitro measured drug metabolizing enzymes using the inbred rat trauma model and the sophisticated techniques of gas-liquid chromatography and high pressure liquid chromatography. 3) to determine the role of biologically generated free radical species in trauma induced pathophysiology using our recently developed spin trapping techniques. 4) to determine the nature and significance of the trauma induced alterations in specific sub-populations of cytochrome P-450 on development.